French patent specification FR-A-No. 1 474 890 describes an apparatus for forcing the flow of fluid from an admission duct to an exhaust duct via a treatment chamber capable of including compression, e.g. by means of a piston 4. The apparatus includes a fluid flow control member 8 mounted to rotate in a cylinder head A which includes at least three non-aligned ports communicating with one another, including an admission port 6 in free communication with the admission duct, an intermediate port 5 in free communication with the treatment chamber, and an exhaust port 7 in free communcation with the exhaust duct. The fluid flow control member 8 rotates and includes an opening 9 which gives the treatment chamber access to only one of the ducts at a time as it rotates (see FIGS. 1 to 5).
The fluid flow control member 8 is driven with continuous rotation under all circumstances and is disposed in the cylinder head in such a manner as to ensure perfect sealing by friction between the treatment chamber and the admission and exhaust ducts (page 1, lines 17 to 25). Sealing may be reinforced by fitting segments 10.
According to said document, said apparatus is used for gas admission and exhaust in spark ignition engines, with the treatment chamber then constituting a combustion chamber containing a conventional internal combustion engine piston 4.
The cylinder head is also provided with a port for insertion of a spark plug 11. It is specified that the apparatus is entirely suitable for internal combustion engines, two strokes, diesels, and engines using any type of fuel (page 2, lines 7 to 9).
French patent specification FR-A-No. 2 090 414 describes a similar fluid flow control apparatus in which the cylinder head (7) is made up of two portions enabling the entire assembly to be machined, which portions are independently clamped into place, with the cylinder head being made of special aluminum, while the shaft (1) and the rings (2 and 8) are specially shaped so as to reduce the coefficient of friction to a minimum and so as to solve problems of expansion.
French patent specification number FR-A-2 184 209 relates to another similar fluid flow control apparatus equally applicable to (spark ignition) internal combustion engines and to compressors or pumps. It is emphasized therein that in apparatus performing the same functions, the systems used (valves controlled by cam shaft(s) often via several intermediate components) slow down fluid flow by constituting obstacles to the passage of fluid into that one of the chambers in the cylinder head which is open to the outside. In addition, the reciprocating motion of such systems constitutes considerable inertia reducing overall efficiency and putting a limit on maximum speed, while the repeated shocks constitute a risk of said components being damaged (page 1, lines 4 to 12).
The use of rotary fluid flow control apparatus serves to avoid these drawbacks and the component parts can be treated so as to be capable of operating in a corrosive medium, thereby making it possible to limit pollution from spark ignition engines by accepting a leaner mixture so as to reduce the quantity of carbon monoxide emitted.
French patent specification FR-A- No. 2 417 636 describes another rotary fluid flow control apparatus used in four stroke engines and completely similar to a fluid flow control component caused to rotate continuously about a horizontal axis perpendicular to the engine cylinder axis.
French patent specification FR-A-No. 1 573 321 describes an internal combustion engine and a discontinuously rotating fluid flow control apparatus using a discontinuous rotary drive system based on a Maltese cross. Such a device has not given rise to practical applications because of the impossibility of obtaining the required sealing and a sufficient speed of rotation with the metals or alloys used for making such engines.
Attempts have been made to improve sealing, for example by having a counterpressure shoe which receives pressure proportional to the pressure in the cylinder as described in FR-A-No. 429 121.
Another solution proposed by Japanese patent specification JP-A-No. 60-17 216 consists in making a rotary fluid flow control valve having a fixed portion 6 and a rotary portion 12 both of which are made of ceramics in order to limit thermal expansion and thus limit loss of sealing. In addition, this solution makes it possible to obtain low friction so there is no need to use a lubricant.
Other solutions have been proposed by the present inventor and constitute the subject matter of several patent applications, in particular the following French patent applications: FR-No. 86 13 525, FR-No. 86 17 438, and FR-No. 86 17 440. In these prior documents by the present inventor, a particularly advantageous application relates to engines, said engines being made of a special ceramic having characteristics of high strength at high speeds of rotation and also having resistance to thermal shock, giving a lifetime which is considerably increased relative to prior ceramics.
Further, in application FR-No. 86 13 525, the inventor describes a discontinuously rotating system in which the system is stationary for 80% of the period of rotation. Such solutions proposed by the present inventor are particularly suitable for engines in which the pistons and the cylinders are oval in shape because of the high level of kinetic and mechanical efficiency of such a system.
However, a major drawback of prior art fluid flow control systems and particularly of rotary control systems lies in lack of sealing when the piston is at top dead center or in the vicinity of top dead center, and in particular at the end of the compression cycle and above all at the moment of expansion on ignition at the precise instant when a shock wave gives rise to a pressure which, in some cases, may be as much as 100 to 150 times the compression ratio, which level is reached in diesel engines.
An object of the present invention is therefore to solve the novel technical problem consisting in supplying a solution which makes it possible to provide substantially perfect sealing in all types of fluid flow control including a treatment chamber which may contain compression and in which a piston reciprocates, when the piston is at top dead center or in the vicinity of top dead center.
Another object of the invention is to solve the novel technical problem consisting in providing a solution making it possible to provide substantially perfect sealing at top dead center or in the vicinity of top dead center of pistons in internal combustion engines, or in piston compressors, or in equipment that operates by pulses, in particular pulse jets.
Another object of the invention is to solve the novel technical problem consisting in providing a solution making it possible to ensure substantially perfect sealing at top dead center or in the vicinity of top dead center with a piston reciprocating in a treatment chamber, said method being equally applicable to conventional two or four stroke engines and to diesel engines, and preventing any mixture taking place between fresh gas being admitted and burnt gas being exhausted, thus preventing any exhaust gas from penetrating into the admission circuit.
Another object of the invention is to solve the novel technical problem consisting in providing a solution making it possible to obtain substantially perfect sealing at top dead center at the end of the exhaust stroke and prior to admission in internal combustion engines, said sealing requiring no greasing nor any adjustment and having no possibility of degrading over time, said sealing thus being incapable of coming out of adjustment regardless of the speed of rotation or the compression ratio, and additionally being very simple.
All of these technical problems are solved for the first time by the present invention in a manner which is particularly simple and useable on an industrial scale.